The effect of targeted magnetic nanoparticles on hepatoma and the underlying mechanism were examined. Nude mice transplanted with a human hepatoma cell line （HepG2 cells） were randomized into 5 groups, including： （1） group A, receiving normal saline, （2） group B, receiving 5-fluorouracil （5-Fu）, （3） group C, receiving magnetic nanoparticles containing 5-Fu, （4） group D, consisting of treatment with magnetic nanoparticles containing 5-Fu and inside magnetic field and （5） group E, receiving pure magnetic nanoparticles and inside magnetic field. Morphological features of transplanted tumors in mice in each group were observed under transmission electron microscope （TEM）. The expression of bcl-2/bax protein was immunohistochemically detected by SABC method. The results showed that a large number of apoptotic tumor cells were found in group B and group D under TEM. The expression of bcl-2 protein was significantly decreased and the expression of bax protein increased significantly in both group B and D as compared with those in group A, C and E （P〈0.01 for all）. The decrease in bcl-2 and the increase in bax were more in group D as compared with group B （P〈0.01）. It is concluded that the targeted magnetic nanoparticles containing 5-Fu can improve the chemotherapeutic effect of 5-Fu by decreasing bcl-2 expression, increasing bax expres- sion and inducing apoptosis of the liver cancer cells.
